This is a Phase III randomized, double-blind study of IDV with open-label ZDV and 3TC with the option to switch from ZDV to open-label d4T for ZDV intolerance at anytime during the study or for disease progression short of a primary study endpoint after the first 24 weeks of therapy. A total of 1750 subjects with HIV infection who have CD4 cell counts <,= 200 cells/mm3 and >,= 6 months prior ZDV therapy will be included. Subjects will be randomly assigned to one of the following two treatments: ARM 1: Open-label ZDV 200 mg TID + open-label 3TD 150 mg BID + IDV placebo TID (q8h) VERSUS ARM 2: Open-label ZDV 200 mg TID + open-label 3TC 150 mg BID + IDV 800 mg TID (q8h)